Czech Polar Reports

Photoprotective mechanisms activated in Antarctic moss Chorisodontium aciphyllum during desiccation

2024-09-26T17:17:40+02:00

We investigated the relationship between relative water content (RWC) of Antarctic moss Chorisodontium aciphyllum and several chlorophyll fluorescence parameters evaluating primary photochemical processes of photosynthesis. During the gradual dehydration of Ch. aciphyllum from fully wet (RWC=100%) to dry (RWC=0%) state, progression of NPQ (non-photochemical quenching) induction curves were recorded; the maximum NPQ (NPQ_max) attained at the end of illumination period (10 min.), and NPQ relaxation in dark were all analysed. Induction curves of photosynthetic electron transport rate (ETR) were also evaluated, as well as two parameters, ETRmax and initial slop, were derived from the curve: (1) ETR_max; (2) initial slope (a parameter). The two parameters were related to the degree of desiccation (RWC decdlining from 100 to 0%). It was found that NPQ induction curves and the parameters derived from them were sensitive to dehydration and may be used as markers for dehydration-induced changes in photosystem II functioning of desiccating Ch. aciphyllum. The activation of non-photochemical quenching during desiccatin and the underlying mechanisms are discussed.

The archaeal community in sediments of freshwater lakes of north-east Antarctic Peninsula: Structure and diversity

2024-09-26T17:46:48+02:00

This research represents the first attempt to study the structure and diversity of the archaeal and methanogenic archaeal community in selected lakes around the Czech polar station J.G. Mendel on James Ross Island (JRI), Antarctica. Sediment samples from a total of 19 of JRI and the nearby Vega Island and Long Island, were analyzed using 16S rRNA and mcrA genes sequencing and real-time qPCR. Contrary to the sequences retrieved by 16S rRNA analysis, many more reads belonging to methanogens were found with mcrA gene sequencing. Generally, archaea represented only a small proportion (0–8.8%) of the total prokaryotic community. With the exception of lakes in the Solorina Valley and Lagoons Mesa area and Lake Esmeralda on Vega Island, methanogenic archaea made up a small proportion of the archaea present in most lakes. The genera Methanothrix and Methanosarcina were identified as the predominant methanogenic representatives in the lake samples. Sequences of representatives belonging to Methanothermobacter sp. and Methanomassiliicoccales and a high proportion of sequences belonging to Methanoperedens-like archaea, methanotrophs that associate anaerobic methane oxidation with denitrification, were recorded for the first time in Antarctica. It is also the first time that the presence of the genus Methanobacterium has been detected to such a large extent. Generally, sequences of the methanogens which might be involved in all three pathways of methane production were found in our samples, indicating the broad metabolic potential of the methanogens present. Individual lakes from one area shared much higher similarity in their methanogenic diversity with the lakes from another area rather than with the lakes within the same area, suggesting that a lake location is probably not the main factor influencing the diversity of the methanogens. Indeed, archaeal and methanogenic community structure and mcrA gene copy numbers varied even within a single lake, suggesting that more sampling within a single lake, preferably at different times of the year, will be necessary in the future for more comprehensive information. Although this is an initial study, our research unambiguously provides evidence that the lakes of the JRI and surrounding islands may be potential sources of new archaeal species or metabolic pathways.

Movements of the bearded seal in the White Sea monitored by satellite telemetry

2024-09-26T18:23:09+02:00

Movements and distribution data of the bearded seal (Erignathus barbatus) in the White Sea during summer and autumn were obtained as a result of tagging with satellite telemetry transmitters (STT). Russian-made Pulsar STTs operated in the Argos system. Catching and tagging of bearded seals was carried out in the Onega and Mezen bays in 2014, 2015 and 2017. Altogether, 7 STTs were installed on seals of different ages and sexes. Analysis of satellite telemetry data showed that during the non-ice period bearded seals were tied to local habitat areas, and the dynamics of their movements differed in the inner and open parts of the sea. The STT data suggest that these differences in distribution are due to lability in feeding and show good adaptation of the bearded seal in the conditions of poorly accessible feed base of the White Sea. The diverse feeding strategy of the bearded seal in the White Sea, and its adaptation to the difficult feeding conditions of the sea, may help the species to survive in the region and ensure stable population numbers in changing environmental conditions.

Photoinhibition and recovery of primary photosynthesis in Antarctic and subantarctic lichens. Analysis of interspecific differences

2024-09-26T18:51:30+02:00

This study meticulously investigates the dynamics of photoinhibition and the mechanisms of primary photosynthetic activity recovery in lichens found in Antarctica and the sub-Antarctic regions. Advanced methodologies were utilised, such as Kautsky's kinetic analysis and the OJIP test. The study carefully details the response of various lichen species to intense light stress, outlining both immediate effects and subsequent recovery processes. Our findings reveal that these lichens employ a range of adaptive strategies, specific to each species, to mitigate the effects of photoinhibition, thereby emphasizing their remarkable resilience and ecological importance in harsh environments. Notably, the investigation reveals the sophisticated interplay between inherent photoprotective mechanisms and the ecological adaptations that enable these lichens to thrive under such harsh conditions. The study not only advances our knowledge of plant physiology under stress but also enriches our insights into the survival strategies of terrestrial organisms facing global environmental changes. Three types of photoinhibitory treatments differing in their duration and strength were applied to 7 lichen species from Antarctica and South America (Isla Navarino). The lichens responded with a decrease in photosynthetic processes in photosystem II (F_V/F_M and Φ_PSII declined), although they showed almost complete recovery in the following 5 h. This was attributed to the activation of photoprotective mechanisms, non-photochemical quenching (NPQ) in particular, during photoinhibitory treatments. Chlorophyll fluorescence parameters derived from slow Kautsky kinetics were correlated with those derived from the OJIP curve. Our study presents data that supports the conclusion of significant photoresistance of the studied lichen species in the hydrated state to photoinhibition induced by high doses of photosynthetically active radiation (PAR).

Profile of inflammatory biomarkers in extreme conditions: Changes of serum amyloid A in a 7-week summer camp in Antarctica (Short Communication)

2024-09-26T19:06:30+02:00

Isolated, confined, and extreme (ICE) conditions faced in Antarctica can influence immune system and inflammatory responses in humans. We evaluated the inflammatory biomarkers serum amyloid A (SAA), transforming growth factor-beta (TGF-β), and fatty acid-binding protein 2 (FABP2). Seven expeditioners took part in a 7-week Antarctic summer camp (Nelson Island) and were evaluated at Pre-Camp (i.e., at the beginning of the ship travel), Camp-Initial (i.e., 4^th and 5^th day in camp), Camp-Final (i.e., 45^th– 46^th day), and at the Post-Camp (on the ship on the return journey). Camping in Antarctica induced a bi-phasic change in SAA, with an increase found at Camp-Initial followed by a return to baseline levels. Such finding indicates a transient acute inflammation that does not imply a chronic inflammation condition in the long term.

Rhizosphere bacterial community influence on Deschampsia antarctica È Desv. adaptability in context of temperature near plants in local spatial scales of Galindez Island, Argentine Islands (the maritime Antarctic)

2024-09-27T08:59:00+02:00

The effect of rhizosphere bacterial community index (I^rb_i) influence on the nine populations of Antarctic hair grass (Deschampsia antarctica) adaptability was studied in the Galindez Island (summer season 2017/18). Moreover, the corresponding influence indices I^rb_i(i=1÷9) and I^rbp_i (p=1÷5 for the most common bacteria) were evaluated as well. The objective was to compare the I^rb_i and I^rbp_i series with the united temperature influence index on plant populations (I^t¹_i(z)) series and the united quality latent index of adaptability I^q¹_i. The study used data on the rhizosphere metagenome composition based on 16S RNA analysis. Methods determining the plant number in populations, and measuring the morphometric indices of D. antarctica populations were used. Reserve and protective seed proteins spectra were studied by polyacrylamide gel electrophoresis. Method of extreme grouping the spatial variables of these indices was applied for nine populations to obtain a I^q1_I and I^t1_iand I^rb_i, I^rbp_i. Sets of united indices were compared by regression technique. A comparative statistical analysis of the I^t1_iand I^rb_i, I^rbp_i sets in this season was carried out. This possible influence appeared to be individual for each D. antarctica studied population. In each population, part of the plants reacted positively to the bacteria influence, while the other part either did not react or reacted negatively. Dependence of the plant adaptation indices on rhizospheric bacterial communities z(x) is shown in our data. This means that the rhizosphere bacterial community and temperature-dependent rhizosphere bacteria (x) can play an active role in plant adaptation of D. antarctica populations (z) to individual temperature conditions in the microscale of Galindez Island from a biological point of view.

Summer Antarctic expeditions in seasonal stations as analogs for long-duration space exploration missions: A critical review

2024-09-27T09:18:46+02:00

This critical review aims to compare the conditions of summer Antarctic expeditions in seasonal stations with key characteristics of long-duration space exploration missions (LDSEM). Utilizing NASA's Analog Assessment Tool and data from the COMNAP Antarctic Station Catalogue, along with scientific literature, the review identifies significant parallels for LDSEM analog research. We assess how seasonal and year-round stations differ and highlight aspects of where seasonal stations serve as a better or worse analog for LDSEM. Key findings include that while summer expeditions allow for more feasible evacuations than winter-overs, their access to medical care is more limited. Crowdedness in summer stations with shared rooms better represents LDSEM conditions than the lower density of winter-over settings. Varying daylight hours in summer stations provide a closer parallel to Mars or Moon surface missions than the continuous darkness of winter-over conditions. Additionally, constant hazards, risk management strategies, isolation, sensory deprivation, workload, leadership structures, autonomy, and communication challenges in summer stations align well with LDSEM scenarios. Conclusively, we propose a shift in perceptions, recognizing seasonal Antarctic expeditions as a valuable analog of planetary LDSEM with several advantages over traditionally accepted winter-over settings. Further comparative and longitudinal studies between seasonal and year-round Antarctic stations should be pursued to enhance LDSEM analog research and support interdisciplinary collaboration. This approach will not only advance progress in space exploration research but also improve the quality of life and safety in remote and extreme environments.

Variability of solar UV radiation in the northern mountains of the Czech Republic, 2020–2021

2024-09-27T09:38:13+02:00

Solar ultraviolet (UV) radiation has a crucial role in many atmospheric processes and a huge impact on living organisms. Its main positive effect is the synthesis of vitamin D, but it also causes problems such as sunburn, skin cancer or eye cataracts. In the mountains, high doses of UV frequently occur due to a specific combination of atmospheric and geographical factors such as a high ground reflection as a consequence of a large number of days with snow cover, or a lower concentration of atmospheric pollutants in comparison to lowland urban regions. This study used measurements of erythemal UV radiation from two high altitude areas: the Hrubý Jeseník Mountains (Vysoká hole meteorological station, 1 464 m a.s.l.) and the Giant Mountains (Luční bouda meteorological station, 1 413 m a.s.l.) in the Czech Republic, during 2020 and 2021. We evaluated the daily and monthly changes in erythemal dose and UV index. The maximum daily dose of 5.0 kJ.m^-2 (8.9 of UV index) was measured on 28 June 2020 at Vysoká hole. The maximal UV index of 10.1 was observed at Luční bouda on 5 July 2020, while the maximum daily dose of 4.9 kJ.m^-2 occurred on 14 June 2021. The main factors that caused changes in solar UV radiation were the amount of cloud cover as well as the total ozone column.

Phenology and biometrical assesment of Petunia × hybrida Grandiflora cultivars in urban ecosystems in Arctic region

2024-09-27T09:55:49+02:00

Six new cultivars of Petunia × hybrida Grandiflora (‘Aphrodita White’, ‘Success Salmon Morn’, ‘Dreams Red Picotee’, ‘Hulahoop Blue’, ‘Limbo Blue’, ‘Falcon Burgundy’) were studied in urbanized areas in the Arctic zone (the city of Polyarnye Zori, the Polar-Alpine Botanical Garden-Institute in Kirovsk). Phenological analysis showed that the flowering duration of the cultivars was almost the same, 90–100 days, except for ‘Success Salmon Morn’ (74 days) and ‘Dreams Red Picotee’ (104 days). Biometrical analysis showed that the maximum diameter of flowers was found in Cv. ‘Hulahoop Blue’, and the minimum was typical for Cv. ‘Falcon Burgundy’. In general, varieties with a flower diameter of 6–8 cm predominated. The number of flowers per plant was low in ‘Falcon Burgundy’ (1–3) and high in ‘Limbo Blue’ (12–16). For other varieties, this indicator varied from 4 to 10. Among the features of agricultural technology, the mandatory three to four weeks of hardening and regular application of fertilizers were highlighted both at the stage of seedlings and adult plants. For the ‘Falcon Burgundy’ cultivar, thickened planting was recommended. The study found that these six new varieties are promising for landscaping cities in the Arctic zone since they showes sufficient level of resistace to the conditions of the region.

Do spectral reflectance indices distinguish between the greenness in three different moss species in moss banks on Galindez Island (Argentine Islands)?

2024-09-27T10:20:23+02:00

Spectral reflectance indices of green state of Warnstorfia fontinaliopsis, Chorisodontium aciphyllum and Sanionia georgicouncinata on moss bank in the Galindez Island (Argentine Islands) were measured using a handheld spectrometer PolyPen RP 410 UVIS (Photon Systems Instruments, Drásov, Czech Republic) within the range of 380–790 nm in order to find suitable ones for effective classification of moss species within the same colour state (green). Among altogether 19 indices tested, there were some which did not differ significantly between the studied species (subgroup 1). Other indices (subgroup 2) were sensitive enough to distinguish one of the studied species from the others, and finally (subgroup 3), they were found statistically significantly different for all studied moss species. Also, the indices calculated at wavelengths typical for UAV spectral cameras (green, red and red edge channels) showed species-specific differences and can be potentially used to distinguish between different mosses within the same green physiological state indicating a good vigor.